Synthesis of Nanocrystalline PZT by Hydrothermal Method

Synthesis of lead zirconium titanate by a simple, low-energy consumption hydrothermalmeans is being reported. The precursor materials have been chosen and the method is tailoredso that the process becomes economical and offers low lead loss. The synthesised powdershave been analysed by FTIR, XRD, SEM, TEM, and TGA. The results show the formation oftetragonal PZT nanoparticles with an average yield of ~75 per cent. On the basis of FTIR, theproduct formation is understood to proceed via the formation of a three metal cation hydroxidecomplex, that under hydrothermal treatment undergoes conversion directly to form the tetragonalphase of lead zirconium titanate

Microwave Combustion Synthesis of Silver Doped Lanthanum Ferrite Magnetic Nanoparticles

Lanthanum ferrite (LaFeO3) and silver doped LaFeO3 powders were synthesized by a single step microwave combustion route using nitrates as precursors and glycine as a fuel. XRD analysis indicated the formation of cubic phase with the dopant peaks at 2θ values of 38.3°, 44.1° and 64.4° apart from the peaks corresponding to LaFeO3. As observed from the transmission electron micrographs, LaFeO3 exhibits particles with a larger size (mean size ~57 nm), significant decrease in particle size is observed for silver doped samples. The magnetic measurements reveal weak ferromagnetic nature of LaFeO3, while silver doped samples are ferromagnetic in nature. Lanthanum silver ferrite (x=0.25, A site) shows maximum coercivity (Hci=480.96G) with hysteresis loop at room temperature which is a clear sign of ferromagnetic ordering. The S shape of the curve implies the presence of domain wall movements in nanoparticles. Thermogravimetric analysis of the samples show stable behavior of the products.Defence Science Journal, 2013, 63(3), pp.285-291, DOI:http://dx.doi.org/10.14429/dsj.63.238

Synthesis of Cobalt Oxide Nanoparticles/Fibres in Alcoholic Medium using y-ray Technique

Nanoparticles of cobalt oxides were synthesised by steady state g irradiation technique using various alcoholic salt solutions of cobalt ions with aniline acting as a stabiliser. Preliminary results were investigated using UV-vis and Fourier transform infra red analysis. The X-ray diffractograms revealed major peaks at 2q values of ~ 36.4°, 39.1°, 44.2°, and 65.7° corresponding to the Co3O4 phase and one peak at ~30.7° (100 per cent intensity) for Co2O3 phase. Lower alcohols yielded particles while fibres were formed in higher alcohols as observed from transmission electron microscopic analysis. Iso-propanol was observed to yield cobalt oxide nanoparticles with highest stability, conversion yield and homogeneity in size. The average measured diameter and length of these fibres were ~29 nm and 130 nm respectively. Energy dispersive spectroscopy supports the formation of cobalt oxide. The X-ray photoelectron spectroscopic results for iso-propanol sample show a peak at 781.6 eV confirming the formation of Co3O4.Defence Science Journal, 2010, 60(5), pp.507-513, DOI:http://dx.doi.org/10.14429/dsj.60.57

Studies on potentiostatically deposited poly(<i>o</i>-toluidine) and poly (<i>m</i>-toluidine) films: A comparative aspect

760-764The optical, thermal and morphological properties of potentiostatically deposited poly (o-toluidine) a nd poly (m-toluidine) have been investigated and compared with each other. The effect of monomer concentration and pH of solution on different properties of films has been reported. The formation of conducting emeraldine phase having peak at ~860 nm is found to be more predominant in the case of poly(o-toluidine) as compared to that observed in poly(m-toluidine). Further, the optical spectra recorded as a function of pH of solution show pronounced formation of additional phases in poly(m-toluidine) films in relation to that noticed in the poly (o-toluidine) films. These differences are explained on the basis of polymerization mechanism and rate of deposition of the two polymers. The thermograms also exhibit variation in terms of the number of steps involved in decomposition as well as final decomposition temperature. These differences might be due to the variation in the fraction of different phases of polymer in each case and also to the molecular weight of the different fragments. The morphology of the polymer, however, does not reveal any difference except the appearance of fibrillar morphology at acidic pH (-1.49) which undergoes transition to granular type at pH 4.07

Evidence for second-order optical nonlinearity in γ-ray induced partially cross-linked polyacrylonitrile

The first direct evidence for second-order nonlinearity in partially cross-linked polyacrylonitrile is reported. The cross-linking in γ -ray-induced polymerized neat acrylonitrile is well supported by UV-vis spectroscopy, FTIR, and <SUP>13</SUP>C CP/MAS solid-state NMR. The second harmonic generation (SHG) powder test was employed to access the preliminary information about the occurrence of second-order nonlinear effect. The second harmonic generation is accomplished without the application of an external electric field, thus illustrating the importance of structural changes imparted by high-energy photon flux. Second-order nonlinearity in the present case is expected due to the small ? conjugation imparted by cross-linking through -C═N across polymeric chains coupled with the noncentrosymmetric molecular structure. Second harmonic intensity as high as 80% of that for powder urea has been observed

Poly(m-chloroaniline): electrochemical synthesis and characterization

The optical, morphological, thermal. and electrochemical properties of elcctrochemicaily synthesized poly(m-chloroaniline) reveal several unique features in comparison with similar well known properties of polyaniline. The nature and position of the halide substituent seem to be sensitive factor affecting the film properties. Optical spectra corresponding to different preparation conditions clearly display the significant role of pH during the formation of the conducting phase as gradual decrease in the ratio of absorbance at ∼850 nm to that of simultaneously produced other oxidation state species obtained by decreasing the protonation level. These results are supported by the IR analysis of the samples. The pintensity of quinoid to benzenoid ring modes [I1576/I1470] is highest at pH of -0.22, and decreases with increasing pH of solution. Intcrcstingly, with increasing pH from -0.22 to 3.3, the morphology of the films show a transition from fibrillar to granular type. The thermal patterns exhibit a positive shift in the final decomposition temperature. The influence of pH of solution on the redox properties of the films is seen in terms of change in shape and current magnitude of cyclic voltammograms